Let X be any finite classical group defined over a finite field of
characteristic p>0. In this paper we determine the fields of rational
invariants for the Sylow p-subgroups of X, acting on the natural module. In
particular we prove that these fields are generated by orbit products of
variables and certain invariant polynomials which are images under Steenrod
operations, applied to the respective invariant linear forms defining X.Comment: 33 page